A ring network is a network protection solution widely applied by operators for networking. The ring network has such advantages as simple configuration, good maintainability, and high reliability. Conventional ring networks include SDH (Synchronous Digital Hierarchy) ring networks and WDM (Wavelength Division Multiplexing) ring networks. With the emergence of packet transport networks, packet ring networks are developed gradually, for example, an MPLS (Multi Protocol Label Switching) ring network protection solution is developed.
The MPLS ring network protection technology is a mature packet ring protection technology in this field. In the MPLS ring network protection technology, the MPLS protection ring is a two-fiber bi-directional ring, on which the working channel and the protection channel are in opposite directions. Under normal circumstances, services are transmitted on the working channel. When a link on the MPLS protection ring fails, the MPLS ring network protection technology provides two switching modes, one is a wrapping switching mode, and the other is a steering switching mode. Either of the two modes may be used to change the service transmission path to guarantee the normal transmission of services when the link fails. When the failed link is restored, the MPLS protection ring transits from the switching state to a wait to restore (WTR) timing state. When the wait to restore timing ends, each node on the protection ring directly enters the Idle (idle) state, the switching state is cancelled, and the service path is restored to the original normal path.
In the prior art, each node on the protection ring is required to have the topology information of the entire ring in the protection switching process; however, if the topology of the protection ring is changed when link failures occur, ring protection abnormality may be resulted.